Re: [osg-users] isCurrent() doesn't really work.
I was just thinking of making isCurrent() virtual and implementing it for each of the windowing implementations. Then in releaseContext, it could check to see if the context being released is actually the current context. It may be nice to get the current GraphicsContext, but the cost of that is someone could change the context using a direct api call and the osg calls would be broken again. Using the native api call internally would prevent that. Having a GetCurrentContext static call like you said could still be implemented, and it could be made more robust by verifying it using the isCurrent() call that works with the system level api. The best it could do, however, if isCurrent() returns false on the suspected current context would be to return NULL. Either way, the GetCurrentContext() call would be an additional feature to fixing isCurrent(). Cheers, David -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=32046#32046 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] isCurrent() doesn't really work.
Hi David, Interesting observation, this is certainly a bug GraphicsContext::isCurrent(). Your suggestion of a method to get the current context sounds like a good means for a new implementation. My suggestion would be to have a static GraphicsContext::getCurrentContext() method, and then have it check the Thread::CurrentThread() against a thread safe map of the contexts that have been made current on each thread. The GraphicContext:makeCurrent() and GraphicsContext::releaseContext() methods would also need to manipulate this map to keep it updated. If you want to dive in a have a bash at implementing this then it'd be appreciated ;-) Cheers, Robert. On Thu, Sep 23, 2010 at 10:18 PM, David Guthrie wrote: > I was looking at the isCurrent call and way contexts and made current and > released. > > isCurrent is not virtual, and simply checks to see if the thread on which the > context was made current matches the current thread. > > Every OpenGL api I've looked at provides a way to get a handle to the active > context, which could be compared to the handle of the context in the > GraphicsContext implementation. That would mean the isContext would always > work. > > Currently something like > > A->makeCurrent(); > B->makeCurrent(); > A->isCurrent(); > > won't work, but it could be fixed pretty easily. > > At the same time, releaseContext() could check to see if the context is > actually the active context and do nothing if it isn't. > > In wgl, glx, agl, and cgl you can call GetCurrentContext with the respective > prefix to accomplish this. Even Qt has QGLContext::currentContext(). > > I'll be happy to implement it in some cases, although I am still working with > 2.8.3 and the changes will have to be ported to the trunk. > > Thanks, > David Guthrie > > -- > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=31999#31999 > > > > > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] isCurrent() doesn't really work.
I was looking at the isCurrent call and way contexts and made current and released. isCurrent is not virtual, and simply checks to see if the thread on which the context was made current matches the current thread. Every OpenGL api I've looked at provides a way to get a handle to the active context, which could be compared to the handle of the context in the GraphicsContext implementation. That would mean the isContext would always work. Currently something like A->makeCurrent(); B->makeCurrent(); A->isCurrent(); won't work, but it could be fixed pretty easily. At the same time, releaseContext() could check to see if the context is actually the active context and do nothing if it isn't. In wgl, glx, agl, and cgl you can call GetCurrentContext with the respective prefix to accomplish this. Even Qt has QGLContext::currentContext(). I'll be happy to implement it in some cases, although I am still working with 2.8.3 and the changes will have to be ported to the trunk. Thanks, David Guthrie -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=31999#31999 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
